Flying part two achievement changed

You don’t have to do the Broken Isles invasions anymore for the legion flying achievement, Defender of the Broken Isles.

This was announced on today’s hotfix and here si the reason from the Dev Team:

Developers’ notes: The rotating Legion Assault schedule is designed to have them active at varying times of day over the course of a given week, to accommodate different work schedules and available free time. We're hesitant to have an Assault last for too long, because they stomp on the entire World Quest content of a given zone for the duration, potentially leaving players with nothing to do there once the Assault is complete. But this design doesn't mesh well with an important achievement that requires completion of all four zones - if anything, it causes stress over scheduling and potentially missing specific zones during the cycle. The Defender achievement was never intended to be a major obstacle on the path to flight in the Broken Isles; its inclusion was more for thematic purposes and completeness. As such, we're removing it from the meta-achievement required to unlock flying.